Many different types of safety outlets have been proposed in the past for use in residential electrical systems, but the prior outlets have all suffered from one or more disadvantages.
One type of outlet proposed in the past used a projecting member integrally mounted on the plug, and which would cooperate with the receptacle to close a contact set, such that in the absence of the projecting member, the contacts would remain open and no current would flow to the object inserted in the receptacle. The disadvantage of this type of receptacle, however, is that it requires modification of each appliance to be used with the receptacle, in order to fit it with an appropriate projecting member to coact with the receptacle. Such a receptacle and plug arrangement is shown in U.S. Pat. No. 3,596,019 to Koester.
Another type of safety receptacle provides one or more pins projecting from the receptacle, so that when a plug is inserted, the body of the plug abuts the pins so as to depress them and close a set of contacts and actuate the flow of current to the inserted plug. One disadvantage of such an arrangement, however, is that the pins are accessible to a child and of course when the pins are depressed, the receptacle is "hot" and the safety aspect is defeated. By recessing the pins, however, the effect of this drawback can be minimized. Such an arrangement is disclosed in U.S. Pat. No. 4,152,557 to Busch, et al.
Still another proposal in the prior art has provided a mechanical see-saw linkage within the receptacle housing. The prongs of the plug are adapted to contact opposite sides of the see-saw thereby depressing the pivot point of the see-saw to close a contact. If only one object (i.e. a nail) is inserted into one of the holes in the receptacle, the see-saw will be unbalanced, such that the pivot point cannot be depressed, and the contacts will not be closed. While such a device would provide advantages, it can only with considerable difficulty be fitted to an outlet having appropriate electrical contacts for conducting the current to the prongs of the plug. Such an arrangement is shown in U.S. Pat. No. 3,617,662 to Miller.
A safety outlet, to be useable, must still meet the needs and demands of the electrical appliance and associated plug with which it is to be used. There must be good electrical contact with the prongs of the plugs which are inserted. A number of prior devices modify existing outlets to such an extent that they no longer provide good electrical connections, and for that reason would not likely be approved by building officials for use in residential applications.
A variety of other devices have been proposed in the prior art, but each has presented its own special drawbacks, with the result that none of the prior art devices is readily available on the market for use. Indeed, the most common type of protective device in use seems to be a simple cap or dummy "plug" made of a dielectric or insulating material, and which is inserted into a conventional (i.e. non-safety type) receptacle when not in use. Because of the shape of the dummy plug, it is difficult for a child to remove it, and of course nothing can be inserted into the receptacle when the dummy plug is in place.
However a significant demand exists for a safety outlet which will effectively prevent the danger of electrical shock to children. For example, when children find and play with electrical outlets, they are used to seeing parents and others inserting something into such outlets, and small children naturally tend to emulate such actions and to put things, i.e. objects such as hairpins, nails, pins, and the like into the holes. Of course too often, they do so with serious injury being the result.
Accordingly a primary object of this invention is to provide a new safety outlet which overcomes the drawbacks of prior art devices.
A further object of the invention is to provide an electrical safety outlet which will minimize the risk of shock to children playinq with the outlet, while still providing good electrical contact, appropriate to meet the requirements of electrical codes, all with no inconvenience to the user.
Another object of the invention is to provide a safety outlet which utilizes a contacting device therein to permit the flow of current to the pins of the plug when inserted, but prevent the flow of current when no plug is inserted in the outlet, or when the plug is partially removed.
Still a further object of the invention is to provide a safety outlet which may be installed in conventional electrical wiring boxes without modification.
Yet a further object of the invention is to provide a safety outlet which may be used in new construction, as well as for replacement outlets in existing installations without modification of the remainder of the electrical system.
Still another object of the invention is to provide an improved safety outlet, which practically eliminates the possibility that a foreign object inserted into the outlet could cause an injury from electric shock.
These and other objects and advantages of this invention will become apparent from the following description of the invention and the description of the preferred embodiments.